Internal combustion engine of the two-cycle type



y 9, 1935. A. L. R. BERNARD 2,007,323

INTERNAL COMBUSTION ENGINE OF THE TWO-CYCLE TYPE Filed Sept. 7, 1955 4 Sheets-She't 1 lNVEN TOR Auguste Louis Rene Bernard a I e K ATTORN EYs July 9, 1935. A. L. R. BERNARD INTERNAL COMBUSTION ENGINE OF THE TWO-CYCLE TYPE 4 Sheets-Sheet 2 Filed Sept. 7, 1933 \NVENTOR Auguste Louis Ren Bernard ATTORNEYS July 9, 1935. A. L. R. BERNARD 2,007,323

INTERNAL COMBUSTION ENGINE OF THE TWO-CYCLE TYPE Filed Sept. 7, 1933 4 Sheets-Sheet 3 INVENTOR j Augusc goms Ren Bernard ATTORNEYS July 9, 1935. l A. L. R. BERNARD 2,007,323

INTERNAL COMBUSTION ENGINE OF THE TWO-CYCLE TYPE Filed Sept. '7, 1953 4 Sheets-Sheet 4 6 6% 10 A f g 11 F INVENTOR Augusgg Louis Rene: Bernard ATTORNEYQ Patented July 9, 1935 r INTERNAL COMBUSTION ENGINE OF THE Two-cram rYPE- PATENT? OFFICE Auguste Louis ,Blen Bernard, Rueil-.-Malmaison,

France, assignor to Society Fusion-Moteurs Rueil-Malmaison, France, a society of France Application September 7, 1933; Serial No. 688,522

In Belgium September 10, 1932 2 Claims; (01; 123 71) My invention relates to internal combustion engines of the two-cycle type comprising for each motor cylinder an airfeed pump that; is not integral with the motor piston. My invention is,

more especially concerned with oil engines of that type. fl

The object of my invention is to provide an internal combustion engineof that type thatis better adapted to j'meet the requirements of actual practice and iniparticular which is simpler of structure, cheaper of manufacture and more reliable of working.

To, thiseffect, according to my invention, in a cylinder ofan engine of the type above referred to, having an outlet port adapted to be uncovered by the motor piston at the end of its downward stroke, I provide a slide valve connected to the piston of the air feed pump in such manner that it stops the exhaust of the burnt gases before the motor piston, in'the course of its upward stroke, again covers said outlet port.

Other features of my invention will appear from the foregoing detailed "description of some embodiments of my invention. In particular I have found it advantageous to provide, in the walls of the motor cylinder, ports communicating with the delivery space of the air .pump and to provide at least one pasage in the skirt'of the motor piston, said ports'and passage being located and dimensioned in such a way that communication between said delivery space and the inside of the crank-case of the motor is open during the "intake stroke of the air pump andcut out during its delivery stroke.

Preferred, embodiments of myinvention wil be hereinafter described with reference to the accompanying drawings, given merely'by way of example, and in which: i

Fig, l is diagrammatic axial sectional view of a two-cycle internal combustion engine of the explosion type, made according to my "invention;

Fig.2 is a diagrammatic axial sectional view of a two-cycle oil engine made according to my invention; H v r 7 Figs. 3 and 4 are partialsectional views, simiiar to Fig. 2, of "the engine shown in this figure corresponding to two different positions 'of'the organs; a

' Figs. 5 and 6 are curves illustrating the working of the engine shown in Fig. 2; 5 i Fig. '7 is a view, similar to Fig; 4, showing angine according to my invention;

- Finally Fig. 8 is a curve illustrating the operationof the engine shown in Fig. 7. V According to my invention, the whole of the internal [combustion engine, with the exception of its air feed pump, of its outlet means, and eventually ofits inlet means, is made of any suitable type, provided that it includes the following characteristics: Firstthe inlet means advantageously consist ofports approvided in the cylinder and adapted 1 to becovered or uncovered by the motor piston in when ,it is moving close to the lower end of its travel, gsaid ports a being then connected to the delivery chamberof the air feed pump. Secondly, at least one outlet port 0 is provided in? the cylinder at a level slightly above thatv of inlet ports a, in the usual manner.

flAdvantageously, said ports a and c are distributed, at different levels, along the whole periphery of the cylinder so as to obtain passages of atotal cross section as large as possible.

In engines including only these organs, that isto say of the usual type for most of the twocycle internal combustion engines, there is the very serious drawback, that the'outlet ports are closed too late,

; 'In order to obviate this drawback, instead of providing, as it has already been done, a stopping organ controlled independently of the air feed pump for stopping the exhaust in due time, I

connect the piston d of said air feed pump with a slide valve 6 adapted to stop the exhaust of the burnt gases before the motor piston-in the .course of its upward movement, closes the outlet port 0. As a matter of fact, piston (1' must have reached the upper end of its travel a certain time provide the last mentioned piston with a slide valve 6 and'to cause said slide valve to coact with ports "fprovided in" exhaust pipe 9. Exhaust will then be stopped at a time that it will be easy to adjust by varying either the positions of the ports that coact with slide .e, or the position of the active edge of said slide valve e, so'that exhaust be as short as desired.

Of .course'the expression active edge above covers port c, port 1 may be open (embodiments of Figs. 2 and 7). v

I have found that it is particularly advan tageous, for a good working of the device according to my invention, to make use of an arrangement of the air feed pump such as shown in the drawings. According to this arrangement, piston d is of annular shape and moves in a chamber surrounding the lower part of the motor cylinder. Ports a may then be directly connected with said chamber.

In the case of such an arrangement of the air feed pump, slide valve e is advantageously made in the form of at least one portion of a cylindrical wall, coaxial with the motor cylinder rigidly carried by 'piston d and extending upwardly therefrom (it being supposed to the engine cylinder is vertically positioned). Preferably, for constructional reasons, slide valve e is given the shape of a continuous cylindrical element.

In order to provide, around the walls of the motor cylinder, the usual cooling means, for instance a water jacket h, I preferably arrange the whole in such manner that said slide valve coacts with cylindrical surfaces disposed on the outside of at least a portion of said cooling means, which may of course externally surround the slide valve,

which will then slide within an annular space.

This arrangement is illustrated by Figs. 2 and 7 of the drawings.

Of course the piston d of the air feed pump, and consequently the slide valve e carried by said piston can be, according to my invention, actuated through any suitable means. Some examples of said means are shown in the accompanying drawings:

Thus, as shown in Fig. 1, the organs above referred to can be controlled through a connecting rod 11 journalled on a special crank pin provided on the engine crank-shaft, said crank pin making an angle of, say, 120 with respect to the crank pin to which is pivoted the main connecting rod. This arrangement is one of the simplest that can be utilized in the case of monocylindric explosion engines.

'It is clear that such an arrangement could be utilized in all cases. However, especially when it is desired to devise an oil engine, it is particularly advantageous to make use, for controlling ton d, and furthermore, advantageously, the

cinematic system thus provided serves to control the fuel injection pump of the engine, either through the intermediary of a cam Z, or through a. set of levers actuated by said cinematic system.

In the case in which such a device is utilized, it is clear that the cinematic system ensures simultaneously, on the one hand the control of the engine are thus obtained according to my invenfuel injection pump, on the other hand the controlof the air. feed pump, and finallythe control of the slide valve e through which the exhaust is out ed at the suitable time.

Although, as explained in the patent application above referred to, the cinematic system in question can be made in a great number of different ways, I have shown in Figs. 2 and '7 a simple embodiment thereof.

A point of the chief connecting rod (interposed between the crank-shaft and the motor piston) is connected through a link m to a bell crank lever 7', pivoted about an axis 11. Said axis may be either stationary or carried by an oscillating link, itself pivoted about a stationary axis which is advantageously located close to the axis of revolution of the engine crank-shaft, or is coaxial with said crank-shaft.

The other arm of said lever 9' is connected to piston d either through a link if axis n is stationary, or through a mere articulation in the other case.

Cam I is, for instance carried by lever 7', in such manner that said cam may'pivot together with said lever.

It will be readily understood that the system thus obtained is both very simple and very strong, comprises a small number of elements, the only revolving element being the crank-shaft.

It should be further noted that the cinematic systems of the type above described produce a quick upward movement of piston 11, which is very favorable to a good filling of the cylinder, said upward movement being particularly quick if, as above stated, the axis of oscillation n of lever a is carried by a link itself pivoted about an axis located close to the axis of revolution of the crank-shaft.

Of course, this feature will also ensure a quick 'cutting off of the exhaust and all the advantages that result therefrom.

Whatever be the embodiment that has been chosen, the operation of the engine according to my invention is as follows:

This operation will be better understood by referring to Fig. which shows two curves B and D corresponding to the movements of pistons b and (1 respectively. In these curves, the angular displacements of the crank-shaft have been plotted in abscissas and the displacements of the active edges of motor piston b and of slide valve e (ports 0 and 7 being supposed to be in line) have been plotted in ordinates.

The horizontal line E corresponds to the upper' edge of ports 0 and f, and the horizontal line A corresponds to the upper edge of inlet ports a.

Under these conditions, it will be understood that the exhaust of the burnt gases corresponds to a period E beginning at the intersection of the downwardly inclined branch of curve B with horizontal line E and terminating at the intersection of the upwardly inclined branch of curve D with the same horizontal line. It is possible (and advantageous) to so adjust things that the abscissa of the last mentioned intersection is smaller than that of the lower dead center 0 of the motor piston.

Admission takes place as long as the curve B is located above the horizontal line A therefore for a period extending symmetrically on either side of the lower dead center 0 of the motor piston.

The optimum conditions of a two stroke cycle tion much more simply than in the case of the simple and reliable control of said suction, as

shown in Figs. 2 to 4.

The arrangement is the following: Piston dis made of such a shape that its inner face d slides directly on the outer wall of the lower portion of the motor cylinder but that slide valve e is of a diameter larger than that of said inner face of piston d, in such manner that, between the slide valve and the upper portion of the motor cylinder, there may be provided a suitable thickness of cooling water.

In the portion of slide valve e that is adjacent to piston d there are provided holes p adapted to' connect the delivery chamber of the air feed pumpwith the annular space of variable volume p existing between the walls of the motor cylinder andthe lower portion of slide valve e, said annular space being limited in an upward direc-' tion substantially at thelevel of ports a, which open directly intogsaid space. 1 y

Thereforethe delivery chamber of the pump is constantly in communication, through holes p, with ports a.

Holes 11 and q are provided in the lower part of the motor cylinder and in the lower part of the cylindrical portion or skirt of the motor piston respectively.

, Said holes q and q are so located that they never register with each other, being located on different angular zones relatively to the axis of the motor piston. j On the other'hand hole q isstopped by the lateral walls of the piston skirt when said piston is in the vicinity of its lower dead point, i. e. during the compression stroke of piston d, so that the delivery chamber of the air pump (said chamber comprising volume 21 communicates only with ports a during said compression stroke (Figs. 2 and. 4)

Passage q connects the inside of the engine crank-case with ports a when piston b is in the vicinity of its lower dead center (Fig. 3).

Finally, there is provided a set of passages 'r in the wall of the cylinder between ports a and passages c 1 or preferably, at least some of the ports a are prolongated downwardly, in order to afford a communication via holes 1 between the inside of the enginecrank-case and space 12 during the whole of the downward stroke of piston d, so as to permit the inflow of air to the air feed pump.

described, in the case in which independentpas sages T have been provided. v

Horizontal zones A R and Q correspond respectively to the passages or ports a, r and q (the two orifices of the last mentioned passage being supposed to be at the same level on the cylinder and the edge d of the lower inner faced of piston 01 having then been suitably offset).

Sinusoids B B B and B respectively show the displacements of th eupper edge of piston b, of the upper edge of passage (1 of the lower edge of the same passage, and of the lower edge of piston 22.

Finally curve I) illustrates the displacements (with the cinematic system disclosed in Fig. 2) of the edge (2 of piston d. It Will be seen that the intersections of these curves, between which the cross hatched parts indicate the closing of the various connecting passages, limit a plurality of zones, overlapping one anotherand corresponding to a communication being established between the inside of the engine crank-case and space a Said zones, starting from the upper dead center of piston 01, correspond to a communication between the crank-case and space 22 A First through passages r and q (zone I); II)Secondly through ports a and passages 11 (zone Then through passages q uncovered simultaneously by the edge d and the lower portion of the piston (zone III) I v'Ihen, finally, through passages 1' and q (zone In the whole of the preceding description, it

has been supposed that the admission to the engine was controlled only through the passage of piston b past ports a. But one may advantageously, according to my invention, instead of utilizing such an arrangement, control the beginning of theadmission by means of slide valve 0, in order that said admission should start only after piston 12, in the course of its downward stroke, has uncovered ports 11 (Figs. '7 and 8).

As a matter of fact, it may be advantageous, under certain conditions, to have the admission start, while piston d is moving upwardly, at an angular distance before the lower dead center that is smaller than the angular distance, after the lower dead center, at which the admission is cut off. It suffices consequently, in order to obtain this result, to cause slide valve 2 to coact with a port '5 provided in the exhaust pipe t (which will be advantageously inclined, for instance at an angle of 45, upwardly toward the cylinder). The beginning of the admission will then take place, after piston b will have uncovered ports a, at a time that will be easy to adjust by determining suitably the position of the port that coacts with slide valve 6 and that of the active edge of said slide valve.

In this case also, the active edge coacting with port s will advantageously be the lower edge of a port .9 provided in slide valve 6 and of 'a sufficient height in order that, when piston 17 is moving upwardly and has just closed port a, port s may still be open.

The operation of the engine that has just been described, as far as admission is concerned, is the followingf This operation will be better understood by referring to the curves B and D of Fig. 8. Said curves correspond respectively to the displacements of the active edge of piston b and to those of the active edge of slide valve e coacting with ports .9 (exhaust). In these curves the abscissas correspond to the angular displacements of the crankshaft and the ordinates to the displace- It can be seen that admission corresponds to a period F beginning at an abscissa corresponding to the intersection of the upwardly extending branch of curve D with the lower edge of port 3 and terminating at an abscissa corresponding to the intersection of the upwardly extending branch of curve B with the upper edge of port s.

Although I have shown the air feed pump concentrically disposed with respect to the motor cylinder, it is obvious that the invention could as well be applied to the case in which said pump is located on the side of the motor cylinder, being either parallel or not to said cylinder.

In a likewise manner, my invention would also apply to the case in which the movement of the slide valve (and eventually of piston (1) would take place in a downward direction instead of in an upward direction when the admission is being opened and the exhaust is being shut off and eventually to the case in which the delivery of the air feed pump would take place in a downward direction.

Generally speaking, while I have described what I deem to be preferred and efficient embodiments of my invention it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of my invention as comprehended within the scope of the appended claims.

What I claim is:

l. A two cycle internal combustion engine including a cylinder provided with at least one outlet port, a piston adapted to reciprocate in said cylinder so as to uncover said port at the end of its downward stroke, an air feed pump for said cylinder, interconnected separate means for actuating said piston and said pump respectively, and a slide valve, operatively connected with said pump for cutting off the exhaust of the burnt gases before the first mentioned piston, in its upward stroke has again covered said outlet port. 2. A two cycle internal combustion engine of the type described, which comprises in combination, a cylinder provided with at least one outlet port, a piston adapted to reciprocate in said cylinder so as to uncover said port at the end of its downward stroke, an air feed pump for said cylinder, a piston for said pump, interconnected separate means for actuating said pistons respectively, and a slide valve operatively connected with the last mentioned piston for cutting off the exhaust of the burnt gases before the first mentioned piston, in the course of its upward stroke, has again covered said outlet port.

3. A two-cycle internal combustion engine of the type described, which comprises in combination, a cylinder provided with at least one outlet port, a piston adapted to reciprocate in said cylinder so as: to uncover said outlet port at the end of its downward stroke, an air feed pump for said cylinder, an annular piston for said pump coaxially' surrounding said cylinder, interconnected' separate means for actuating said two pistons respectively, and a slide valve rigidly connected to the second mentioned piston for cutting off the exhaust of the burnt gases before the first mentioned piston, in the course of its upward stroke, has again covered said outlet port.

4. A two-cycle internal combustion engine of the type described, which comprises in combination, a cylinder provided with at least one outlet port, an exhaust pipe connected to said outlet port, a piston adapted to reciprocate in said cylinder so as'touncover said outlet portat the end of its downward stroke, a member rigidly fixed to said pipe provided with a housing having the shape of at least a portion of a cylinder coaxial with the first mentioned cylinder, said housing extending around the whole of the periphery of the inside of said pipe and communicating directly therewith, an air feed pump for the first mentioned cylinder, an annular piston for said pump coaxially surrounding said cylinder, interconnected separate means for actuating said two pistons respectively, and a cylindrical shaped slide valve rigidly carried by the second mentioned piston and fitting in said housing for closing the exhaust of the burnt gases before the first mentioned piston, in the course of its upward stroke, has again covered said outlet port.

5. A two-cycle internal combustion engine according to claim 4 further comprising cooling means forthe engine cylinder disposed between said cylinder and the member rigidly fixed to the exhaust pipe that is provided with a housing for the slide valve.

6. A two-cycle internal combustion engine of the type described, which comprises in combination, a cylinder provided with at least one outlet port, a piston adapted to reciprocate in said cylinder so as to uncover said port at the end of its downward stroke, an air feed pump for said cylinder, a piston for said pump, a crank shaft for said engine, a connecting rod interposed between said crank shaft and said first mentioned piston, a crank pin on said crank shaft for said connecting rod, a second crank pin making a determined angle with the first mentioned crank pin, a connecting rod pivoted at both ends to said second mentioned crank pin and to said second piston respectively, and a slide valve operatively connected with the last mentioned piston for cutting off the exhaust of the burnt gases before the first mentioned piston, in the course of its upward stroke, has again covered said outlet port.

7. A two-cycle internal combustion engine of the type described, which comprises in combination, a cylinder provided with at least one outlet port, a piston adapted to reciprocate in said cylinder so as to uncover said port at the end of its downward stroke, an air feed pump for said cylinder, a piston for said pump, a crank shaft for said engine, a connecting rod interposed between said crank shaft and said first mentioned piston, a pivoting lever, articulated means for connecting said lever at one end to said second mentioned piston, articulated means for connecting the other end of said lever to said connecting rod, and a slide valve operatively connected with the last mentioned piston for cutting 01f the exhaust of the burnt gases before the first mentioned piston, in the course of its upward stroke, has again covered said outlet port.

8. A two-cycle internal combustion engine including a fuel feed pump, made according to claim 7, further comprising means, operatively connected to said pivoting lever, for controlling said fuel feed pump.

9. A two-cycle internal combustion engine of the type described, which comprises in combination, a cylinder provided with at least one outlet port, a piston adapted to reciprocate in said cylinder so as to uncover said port at the end of its downward stroke, an air feed pump for said cylinder, a piston for said pump, a crank shaft for said engine, a connecting rod interposed between said crank shaft and said first mentioned piston, a bell crank lever pivoted about an axis station ary with respect to theengine frame, a link piv: oted at one: end 1509118 endof saidilever'andat the other end to said connecting rod, a link pivoted at'one'cnd to'the other end of said bell crank lever and at the other end tosaid second. men-. tioned piston, and a slide valve foperatively con-' nectedwith thelast mentioned piston tor cutting off the exhaust of the: burnt gases be'forethe first mentioned piston, inthe'course of its upward strokahas again covered said outletport,

10., A two-cycle internal combustion engine including a fuel feed pump, made according to claim 9, further comprising a cam carried by said bell crank lever forIoontrolling said' fu'el feed pump.

I 11. A two-cycle internal combustion engine of the type described, which comprises in combination, a crank-case a cylinder. provided with at least one outlet port and with'at least one inlet port, a piston adapted to reciprocate in said cylinder so as to uncover said outlet port and said inlet port successively atthe end of its downward stroke, an air feed pump for-said cylinder, a piston for said pump, interconnected distinct means for actuating said pistons respectivelyfa slide valyepperatively connected with, the last mentioned pistonior cutting oiT the exhaust of the burnt gases before the first mentioned piston, in the course ot its upward stroke, has-again covered saidoutlet port, and means i or connecting the'delivery space of said pump with the inside of said crank-case during the intake stroke of said pump and with the inlet port during the delivery of said pump. 7 l I c n c 12. A two-cycle internal combustion engine of the type described; which comprises in combina tion, a crank-case,- a cylinder provided with at least one outlet portand at least one inlet port, a piston adapted to reciprocate in said cylinder so as to uncover said outlet port and said inlet port successively at the end of its downward stroke, an air feed pump for said cylinder, an annular piston for said pump fitting slidably at its lower end about said cylinder andcoaxially surrounding it at its upper end so as, to leave empty space around said cylinder, interconnected distinct means for actuating said pistons respectively, a-slidevalve 'operatively connected with the last mentioned piston for cutting oil the exhaust of the burnt gases before the first mentioned piston, in the course of its upwardstrokc, has again covered said outlet port, said first men: tioned piston, said'cylinder and said. slide valve beinglprovided with ports so disposed that said empty space is in communication with the inside of said crank case during the intake-stroke of said pump and with the inlet port during the delivery stroke of said pump.

13. A two-cycle internal combustion engine of the type described, which comprises in combination, a crankcase, a cylinder provided with at least one outlet port and at least one inlet port, a motor piston adapted to reciprocate in said cylinder so as to uncover said outlet port and said inlet port successively at the end of its downward stroke, said piston comprising a skirt, an exhaust pipe connected to said outlet port, an air feed pump for said cylinder, an annular piston for said pump fitting slidably at its lower end about said cylinder and coaxially surrounding it at its upper end so to form an empty chamber around said cylinder, interconnected distinct means for actuating said pistons respectively, a sliding element rigidly connected to the second mentioned piston adapted to cut ofij the outflow through said exhaust pipe before the first mentioned piston, in the courseof its upward stroke, has-covered said outletport,said sliding element extending upwardly from the top' of said second mentioned piston, a pump body surrounding the second mentioned'piston so as to form an air compression chamber above said second mentionedpiston, said sliding element being provided with an aperture affording a constant communication between said compression chamber and the empty chamber around the cylinder, the lower portion of the cylinder being provided with a port, and the lower portion of the'first mentioned piston being also provided with a port, the two last mentioned ports being located on difierent angular zones relatively to the axis of said motor piston 50- that they never register, that the last mentioned port in the cylinder is closed by the skirt of the motor piston when said piston is in the vicinity of its lower dead point thereby permitting the delivery of the pump to the cylinder through said inlet port, and that the port provided in the first mentioned piston registers with the inlet port of the cylinder when said first mentioned piston is close,

necting rod interposed between said crank shaft and the first mentioned piston, a pivoting lever, jointed means for connecting one end of said lever to the second mentionedpiston, jointedmeans for connecting the other end of said lever to said connecting rod, and means for connecting the fulcrum of said lever to said cylinder.

15. An internal combustion engine according to lclaim 13, in which the interconnected distinct means for actuating said pistons respectively comprise, acrank shaft for said engine, a connecting rod interposed between said crank shaft and said first mentioned piston, a bell crank 1ever pivoted about an axis stationary with respect to the engine frame, a link pivoted at one end to one end of said lever and at the other end to said connecting rod, and a link pivoted'atone end to the other end of said bell crank lever and at the other end to said second mentioned lever. I

16. An internal "combustion engine according to claim 11 further comprisingmeans for admitting fresh air to said pump for the whole of the downward stroke of the second mentioned piston; v 17. An internal'combustion engine according to claim l2'in which the cylinder is further provided withjports located between the inlet ports and theother ports provided therein so thatsaid empty space isin communication; either via the inlet port, or via the last mentioned ports in the cylinder, for the whole of the downward stroke of the second mentioned piston, with the inside of the crankcase.

18. An internal combustion engine according to claim 13 in which the cylinder is further provided with ports located between the inlet port and the other ports provided therein so as to connect the empty chamber that surrounds the cylinder with the inside of the crank-case for the whole of the downward stroke of the second mentioned piston.

19. A two-cycle internal combustion engine including a cylinder provided with at least one outlet port and one inlet port, a piston adapted to reciprocate in said cylinder so as to uncover said outlet port and said inlet port successively, at the end of its downward stroke, an air feed pump for said cylinder, interconnected distinct means for actuating said piston and said pump respectively, and a slide valve, operatively connected with said pump, for cutting ofi the exhaust of the burnt gases before the piston, in the course of its upward stroke, has covered said outlet port, and for cutting oil. the inflow to the inlet port until after said piston, in the course of its downward stroke, has uncovered said inlet port.

20. A two-cycle internal combustion engine according to claim 13 further comprising an inlet pipe connected with said inlet port and adapted to be shut off by said sliding element, said sliding element being further provided with a port so positioned that the inlet pipe is opened only after the first mentioned piston, in the course of its downward stroke, has uncovered said inlet port.

21. A two-cycle internal combustion engine of the type described, which comprises in combination, a cylinder provided with at least one outlet port, a piston adapted to reciprocate in said cylinder so as to uncover said port at the end of its downward stroke, an air feed pump for said cylinder, a piston for said pump, interconnected separate means for actuating said pistons respectively, and a slide valve outside said cylinder operatively connected with the last mentioned piston for cutting off the exhaust of the burnt gases before the first mentioned piston, in the course of its upward stroke, has again covered said outlet port.

22. A two-cycle internal combustion engine including a cylinder provided with at least one outlet port and at least one inlet port, said outlet port being at a higher level than said inlet port, a motor piston adapted to reciprocate in said cylinder so as to uncover said outlet port and said inlet port successively, an air feed pump for said cylinder, interconnected separate means for actuating said piston and said pump respectively, and a slide valve, operatively connected with said pump for cutting off the exhaust of the burnt gases before the first mentioned piston, in its upward stroke, has again covered said outlet port.

23. A two-cycle internal combustion engine, which comprises in combination a crank case, a cylinder provided with at least one outlet port and at least one inlet port, a piston adapted to reciprocate in said cylinder so as to uncover said outlet port and said inlet port successively at the end of its downward stroke, an air feed pump for said cylinder, an annular piston for said pump fitting slidably at its lower end about said cylinder and coaxially surrounding it at its upper end so as to leave an empty space around said cylinder, interconnected distinct means for actuating said pistons respectively, a slide valve operatively connected with the last mentioned piston for cutting off the exhaust of the burnt gases, said cylinder and said slide valve being provided with ports so disposed that said empty space is in communication with the inside of the crank case during the intake stroke of said pump and with the inlet port during the delivery stroke of said p p.

24. A two-cycle internal combustion engine of the type described, which comprises in combination, a crank case, a cylinder provided with at least one outlet port and at least one inlet port, a motor piston adapted to reciprocate in said cylinder so as to uncover said outlet port and said inlet port successively at the end of its downward stroke, said piston comprising a skirt, an exhaust pipe connected to said outlet port, an air feed pump Ior'said cylinder, an annular piston for said pump fitting slidably at its lower end about said cylinder and coaxially surrounding it at its upper end so as to form an empty chamber around said cylinder, interconnected distinct means for actuating said pistons respectively, a sliding element rigidly connected to the second mentioned piston adapted to cut oil the outflow through said exhaust pipe, said sliding element extending upwardly from the top of said second mentioned piston, a pump body surrounding the second mentioned piston so as to form an air compression chamber above said second mentioned piston, said sliding element being provided with an aperture affording a constant communication between said compression chamber and the empty chamber around the cylinder, the lower portion of the cylinder being provided with a port, and the lower portion of the first mentioned piston being also provided with a port.

25. An internal combustion engine according to claim 23 in which the cylinder is further provided with ports located between the inlet ports and the other ports provided therein so that said empty space is in communication, either via the inlet port, or via the last mentioned ports in the cylinder, for the whole of the downward stroke of the second mentioned piston, with the inside of the crank case.

26. An internal combustion engine according to claim 24 in which the cylinder is further provided with ports located between the inlet port and the other ports provided therein so as to connect the empty chamber that surrounds the cylinder with the inside of the crank case for the whole of the downward stroke of the second mentioned piston. I

AUGUSTE LOUIS R NE BERNARD. 

